Production of composite photographic images



y 23, 1939- H. D. MURRAY AL 2,159,600

PRODUCTION OF COMPOSITE FHOTOGRAPKI C IMAGES Filed Feb. 2, 11937 BASE.

PRINTED WITH RED FILTER RECORD BLUE SENSITIVE 'EMULSIONI-YELLOW DYE BLUE FILTER RECORD PRINTED BY PANCHROMATIC EMULSION INFRA'RED LIGHT THROUGH THE SUPPORT If BLUE DYE GREEN FILTER. RECORD PRINTED on T0 I THE SURFACE OF THE EMULSION Patented May 23, 1939 PAT ENT OFFICE I 2,159,500 PRODUCTION OF COMPOSITE PHOTO- GRAPHIC Veracol Film Syndicate land, aBritish company IMAGES Humphrey Desmond Murray and Douglas Arthur Spencer, London, England, assignors to The Limited, London, Eng- Application February 2, 1937, Serial No. 123,668

H In Great Britain February 6, 1936 15 Claims.

This invention consists in improvements in or relating to the production of composite photographic images and has for an object, to provide a method whereby two superposed photographic 5 images maybe produced at different levels in an emulsion layer which may be a single uniform layer or a composite layer formed by two or more superposed emulsion coatings. A further object is to provide a method whereby the images,

10 which may be colour separation records, may be produced in colour so that the final composite picture appears in approximately natural colours.

The invention consists in the method of producingtwo photographic images superposed in a 5 light sensitive emulsion layer which consists in exposing opposite sides of the layer toform latent images at those sides respectively and developing the layer from one surface thereof by the use of two developers in succession one adapted pref- M erentially to develop the image nearer to the surface. of the layer to whichit is applied and the other to develop preferentially the image remote from that surface. j 1

In the preferred form of the invention the Y latent images correspond to, difi'erent colour sensations of the subject and the developers employediinclude-colour forming substances adaptedto develop, with the silver images which are subsequently dissolved away, images in the appropriate colours.

Substances which, when added to a developer, cause development to proceed more rapidly in thedepths of an emulsion than on the surface are those which form highly insoluble compounds with silver salts, for example soluble iodides and sulphides such as those of sodium and potassium, and those which form complex salts with silver salts such 'as thiosulphates and cyanides. All these substances are believed to be characterized by the fact that they reduce-the concentration .of free silver ions in the emulsion; Of the substances available which cause development to proceed more rapidly in the depths of an emulsionthan on the surface we have found that iodides are not entirely satisfactory as they appear to interfere with the full production of colour. Sulphides are also unsuitable as they cause blackening and fog'. Potassium cyanide may be used or sodium thiosulphate. We prefer 50 the latter substance addedin smallconcentrations,to the developing solution. One method of carrying out the .invention is to expose a light sensitive emulsion, preferably dyed with a yellow dye, first from the front side i of the emulsion, and then through the supporting base for the emulsion; The emulsion is first developed with a known colour developing solution, to which has been added a high proportion of an inorganic salt to prevent excessive swelling of the emulsion, until the surface image is fully developed. It is washed and development is continued in a second colour developer containing a smallquantity of a substance which depresses the concentration of free silver ions, for example a soluble thiosulphate oriodide such as sodium or potassium thiosulphate or sodium or potassium iodide. The exact quantity must be found by trial and error to suit the developer used and the thickness of the emulsion. The second solution develops the image in the depths of the 16 emulsion without producing substantial further development in the surface of the emulsion. The developed silver images. are then bleached fixed and washed producing two superposed colour imageson a single support as indicated diagram- 20 matically in Figure 1.

A second method of carrying out the invention to produce a photograph of the form indicatedin Figure 1 is to expose an emulsion, preferably dyed with yellow dye, first from the front side of the" emulsion and then through the supporting base, and develop the surface image with an energetic developer in which development is completed in less than one minute and which is loaded with inorganic salts or glycerine to delay its penetration into the depths of the emulsion. Such energetic developers are well known and normally contain a vigorous accelerator such as sodium hydroxide or concentration of potassium carbonate exceeding 6% in place of the more usual sodium carbonate. This surface developer may not be a colour developer'and may produce a normal photographic image insilver. The image near the base is then developed with a depth developer of the type described containing sub- 0 stances which depress the concentration of silver ions and at the same time producing a colour image of the type characteristic of the so-called colour developers. The surface silver image is then converted to a coloured image by any of 5 the well known colouring processes such as chemical toning, dye toning or the method revealed in British patent specification No. 377,706.

As an example of another way of carrying the invention into effect, an ordinary blue sensitive 5 bromide" emulsion stained with tartrazine to prevent light penetrating through the-emulsion, and coated on glass was exposed through the back through a negative and from the front through another negative. The plate was developed with a metol developer giving even development in the depths and on the surface of the emulsion and was then fixed, washed thoroughly to remove tartrazineand dried.

This left two images, one on thesurface and one in the depths of the emulsion. The whole was bleached in (When dissolved (a) and (b) are mixed) until the top image was developed. The effect of the added sodium sulphate is to delay penetration of the developer into the depths of the emulsion. The plate was rinsed in an aqueous solution of 1% acetic acid, washed thoroughl and immersed in (a) Diethylparaphenylenediamine hydro- .(When dissolved (a) and (b) are mixed) until the bottom image was developed. It was thoroughly washed and the silver removed with Farmers reducer. On washing and drying the emulsion showed a magenta image overlying a yellow one.

The same procedure can be applied to two emulsion layers coated one on top of the other and separated by a yellow filter layer to prevent light striking through as shown in Figure 3.

As an alternative, the two developers given may be applied to the direct development of images formed on the surface and in the depths of a blue sensitive emulsion layer dyed yellow, or of two emulsion layers separated by a suitable filter layer. After thoroughly washing, the residual developed silver and the unchanged silver salt is removed in Farmer's reducer.

The invention is also applicable to the processing of the so-called double coated kinematograph film in which emulsions are coated on either side of the support. In this case the coating on one side of the support has a different spectral sensitivity to that on the other side.

One example of such a material is indicated diagrammatically in Figure 2 and method of processing is as follows.

One side of the support base has a coating of a bluesensitive emulsion ofthe lowest coating weight consistent with the maintenance of good photographic gradation and containing a water" soluble yellow dye. The other side is coated with an emulsion which is panchromatic or one which has been specially sensitised to red and infra-red light. This red sensitive emulsion may contain a suitable inert blue dyestuif which is removable during processing and which limits the penetrability of red light. I

remote from the support).

light by methods obvious to those skilled in the.

art. For example the red filter record could be printed by blue light on to the coating which is blue sensitive only, its penetration through the support being prevented by the inert yellow dyestufi. The blue filter record is printed'on the red sensitive emulsion at a position in its depth close to the support by means of infra-red light, exposure being made through the unsensitised blue sensitive emulsion and the support. The green filter record is printed by blue, or red light, exposure being new onto the surface of the red sensitive emulsion (i. e. at a position in its depth In processing, the first development, using an energetic developer as described above, develops the only image recorded in the blue sensitive emulsion and the'surface image in the red sensitive emulsion, whilst the second development, with the developer containing substances which depress the concentration of free silver ions, develops the image nearer the support in the red or infra-red sensitive emulsion.

It will be obvious to those skilled in the art that, by a suitable choice of sensitised emulsions and inert screening, dyes, the invention is also applicable to the making of three superimposed colour separation negatives on a double coated film when this is processed by the methods now revealed and that these negatives can, if desired, be reversed to positive images and coloured to form a three colour positive picture in the known manner.

Colour developing solutions may contain a developing agent which is by itself capable of producing colour. Such developers are indoxyl and I thioindoxyl. Colour development may also be obcases when development is to be effected in the depth of the emulsion the, colour developing solution will contain the developer proper together with a substance according to the present invention capable of depressing the concentration of free silver ions, whilewhen development is to be effected at the surface of the emulsion the colour developing solution will contain the developer proper together with a substance which decreases the rate of penetration of the developer through the emulsion. We claim:

1. In a method of producing a photograph in colors, the step which comprises developing a photographic element containing at least one silver halide photographic emulsion having a developed outer surface image and an undeveloped inner image remote from said surface, said images being in superposed relationship and on the same side of a support, by treatment from the same side as the developed surface image, with a depth color developer containing a substance selected from the group consisting of soluble thiosulphates, soluble cyanides and soluble iodides in such concentration that said depth color developer developing the outer image in a developer which contains an agent which restricts the penetration of such developer to the depth of the outer image,

a and thereafter, without any intermediate fixing step, developing the inner image in a color developer which contains a soluble thiosulphate in such concentration that the said color developer situated one above theother in one or more silver develops the inner image without further developing action on the outer developed'image.

3. The method of developing two latent photographic images situated one above the other in one or more silver halide emulsion layers attached to one side of a support in the production of a photograph in color, which comprises first developing theouter image in a developer which contains an agent which restricts the penetration of such developer to the depth of the outer image, and'thereafter, without any intermediate fixing step, developing the inner image in a color devel-,

oper which contains a soluble cyanide in such concentration that the said color developer develops the innerimage without further developing action on the outer developed image.

4. The method of developing two latent photographic images situated one above the other in one or more silver halide emulsion layers attached toone side of a support in the production of .a photograph in color, which comprises first developing the, outer image in a developer which contains an agent which restricts the penetration of such developer to the depth of the outer image,

and thereafter, without any intermediate fixing step, developing the inner image in a color developer which contains a soluble iodide in such concentration that the said color developer develops the inner image without further developing action on the outer developed image.

5. The method of producing a multi-color photograph from two latent color separation records halide emulsion layers which consists in developing both images simultaneously with,a black-andwhite developer, bleaching the images, re-developing the outer image in a developer which contains an agent .which restricts the penetration of such developer to the depth of the outer image, thereafter, without any intermediate fixing step. developing the inner image in a color developer which contains a soluble thiosulphate in such concentration that the said color developer develops the inner image without further developing action on the outer developed image and thereafter treating the outer image to convert it into a color image.

6. The method of producing a multi-color photograph from two latent color separation records situated one above the other in one or more silverhalide emulsion layers which consists in developing both images simultaneously with a black-andwhite developer, bleaching the images, re-developing the outer image in a developer which contains an agent which restricts the penetration of such developer to the depth of the outer image, thereafter, without any intermediate fixing step, developing the inner image in a color developer which contains a soluble cyanide in such conceittration that the said color developer develops the inner image without further developing action on the outer developed image and thereafter treating the outer image to convert it into a color image.

7. The method of I producing a multi-color photograph from two latent color separation records situated one above the other in one orv more silver halide emulsion layers which consists in developing both images simultaneously with a black-and-white developer, bleaching the images, re-developing the outer image in a developerwhich contains an agent which restricts the penetration of such developer to the depth of the outer image, thereafter, without any intermediate fixing step, developing the inner image in a color developer which contains a soluble iodide in such concentration that the oper which contains an agent whichrestricts the penetration of such developer to the depth of the outer image thereafter, without any intermediate fixing step, re-develop ing the inner image in a second color developer containing a soluble thiosulphate in such concentration that such' second color developer develops the inner image Without further developing action on the outer developed image.

9. The method of producing a multi-color photographic image from two latent color separation records situated one above the other in one or more silver halide emulsion layers attached to one side of a support which consists in developing both images simultaneously with a black-and-white developer, bleaching the images, re-developing the outer image in a color developer which ,contains an agent which restricts the penetration of such developer to the depth of the outer image, thereafter, without any intermediate fixing step, re-developing the inner image in a second color developer containing a soluble cyanide in such concentration that such second color developer develops the inner image without further developing action on the outer developed image.

10. The method of producing a multi-color photographic image from two latent color separation records situated one above the other in one ore more silver halide emulsion .layers attached to one side of a support which consists in developing both images simultaneously with a black-and-White developer, bleaching the images, re-developing the outer image in a color developer which contains an agent which restricts the penetration of such developer to the depth of the outer image, thereafter, without any intermediate fixing step, re-developing the inner image in a second color developer containing a soluble iodide in such concentration that such second color developer develops the inner image without further developing action on the outer developed image.

11. .The method of developing two latent' photographic images situated one above the other in at least one silver halide emulsion layer attached to one side of a support in the production of a photograph in colors, which comprises developing the outer image in a developer containing an agent which restricts the penetration of such developer'to the depth of the outer image andthereaiter developing the inner image in a color developer which contains an agent selected irom the group consisting of soluble duction of a photograph in colors, which com'- prises developing the outer image in a color developer which contains an agent which restricts the penetration of such developer to the depth of the outer image, and thereaftenwithout any intermediate fixing step, developing the inner image in a secondcolor developer which contains an agent selected from the group consisting of soluble thiosuiphates, soluble cyanides and soluble iodides in such concentration that such second color developer develops the inner image without further developing action on the outer developed image.

13. The method of producing photographic color separation records which consists in exposing a sensitive emulsion layer from opposite sides with suitable precautions to restrict the eifect of the exposures substantially to the sides of the layer from which they are made, respectively, and to the diflerent color sensations of the subject, and developing the two latent images by first developing the outer image in a developer which contains an agent which restricts the penetration oi! such developer to the depth of the outer image, and thereafter developing the inner image in a color developer which contains an agent selected from the group consisting of soluble thiosulphates, soluble cyanides and soluble iodides in such concentration that such color developer develops the inner image without further developing action on the outer developed image.

14. The method of, producing a multi-color photograph from two latent color separation records situated one above another in a silver halide emulsion layer vwhich consists in developing both images nmmtaneouny with a blackand-white developer, bleaching the images, redeveloping the outer image in a non-color developer which contains an agent which restricts the penetration of such developer to the depth of the outer image, thereafter, without any intermediate fixing step,: re-developing the inner image in a color developer which contains an agent selected from the group consisting of soluble thiosulphates, soluble iodides and soluble cyanides in such concentration that the said color developer develops the inner image without further developing action on the outer developed image, and then treating the outer image to convert it into a color image.

15. The method of producing a multi-color photographic image from two latent color separation records situated one above the other in at least one silver halide emulsion layer attached to one side of a support, which consists in developing both images simultaneously with a black-and-white developer, bleaching the images, re-developing the outer image in a color developer which contains an agent which restricts the penetration of such developer to the depth or the outer image, and thereaiter, without any intermediate fixing step, re-developing the inner image in a second color developer which contains an agent selected from the group consisting of soluble thiosulphates, soluble cyanides and soluble iodides in such concentration that the said second color developer develops the inner image without further developing action on the outer developed image.

' HUMPHREY DESMOND MURRAY.

DOUGLAS ARTHUR SPENCER. 

